The present invention relates generally to the field of ball type yarn tension devices, and more particularly, is directed to a vertical ball tension control incorporating improved threading means.
Prior workers in the art have developed various types of yarn tensioning devices which include a vertical passageway or channel within which are positioned a plurality of balls. The channel terminates downwardly in a ceramic insert upon which the lowermost of the balls seats for yarn tensioning purposes. The yarn is tensioned by the action of the lowermost ball in known manner by squeezing the yarn against the seat as the yarn is fed through the tensioning device. Examples of such prior art ball tensioning devices are shown and described in U.S. Pat. Nos. 3,753,535 to Zollinger and in 4,030,684 to Levin.
As disclosed in the said patents, the prior art yarn tensioning devices include a housing which defines a cylindrically shaped, vertically oriented yarn passageway. The yarn passageway is downwardly defined at the lower end thereof by a ceramic yarn eye insert which provides a seat for the lowermost ball within the passageway so that the ball normally remains seated at the top of the insert. Usually, a threading device, such as latchless knitting needle is inserted through the yarn passageway and through the ceramic insert by displacing the balls as necessary to pull the yarn through the device. Threading the prior art ball tension devices has usually presented problems because the physical size of the balls and the restricted diameter of the ball chamber have usually rendered it impossible to thread the device in a single pass with a straight threading instrument. Once the yarn is properly threaded for feeding to a weaving, knitting or other similar yarn employing machine, the ball will then return automatically to its seat for yarn tensioning in the usual manner.
In the case of heavy yarns, for example yarns suitable for use with carpets, it is presently the practice to provide ball tension devices of similar configuration, which devices are fabricated of increased dimensions and which utilize larger and heavier balls. The use of such heavy balls renders these presently available yarn tensioning devices relatively more difficult to thread. Additionally, many of the heavy yarns utilized with the large ball tension devices produce excessive quantities of lint when passing through the device, which lint tends to collect within the yarn passageway to thereby impede the function of the balls or to otherwise build up on the inner surfaces of the yarn passageway.